
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title> 
    
    <style>
        table {
          border: 1px solid #000;
          text-align: center;
          width: 240px;
        }
        th,td {
          border: 1px solid #000;
        }
        h3 {
          position: relative;
        }
      </style>
</head>
<body>
    <div id="app">
        <h3>小黑的礼物清单</h3>
        <table>
          <tr>
            <th>名字</th>
            <th>数量</th>
          </tr>
          <tr v-for="(item, index) in list" :key="item.id">
            <td>{{ item.name }}</td>
            <td>{{ item.num }}个</td>
          </tr>
        </table>
    
        <!-- 目标：统计求和，求得礼物总数 -->
        <p>礼物总数：{{totalCount}} 个</p>
      </div>
      <script src="./vue.js"></script>
      <script>
        new Vue({
          el: '#app',
          data: {
            // 现有的数据
            list: [
              { id: 1, name: '篮球', num: 7 },
              { id: 2, name: '玩具', num: 2 },
              { id: 3, name: '铅笔', num: 5 },
            ]
          },
          computed: {
            totalCount() {
              // 基于现有的数据，编写求值逻辑
              // 计算数组里面的 num 属性的总和
              return this.list.reduce((sum, item) => sum + item.num, 0);
            }
          }
        });
      </script>
</body>
</html>
